1. Field of the Invention
The present invention relates to an oral composition such as a dentifrice suitable for use in a vertical pump type container. More specifically, it relates to an oral composition having a good shape retentionability even when prepared as a low viscosity composition, having a good extrudability from a pump type container, and having an excellent feeling and taste when used.
2. Description of the Related Art
Recently, various vertical pump type containers capable of squeezing toothpaste therefrom only by pushing a press-operating portion such as a button have been proposed in, for example, Japanese Unexamined Utility Model Publication (Kokai) Nos. 54-34641 and 55-38783 and Japanese Unexamined Patent Publication Nos. 57-68367 and 57-68368, and it has been found that the use of toothpaste contained in such pump type containers is commercially viable. However, conventional toothpaste formulations are not suitable for use in such pump type containers, because toothpastes suitable for use in such pump type containers should preferably have a viscosity lower than that of conventional toothpastes, from the viewpoint of the structure of the container, so that the extrudability of the toothpastes from the container is made highly satisfactory. Furthermore, the toothpaste is required to have good shape retentionability when the toothpaste is placed on a toothbrush, even when the toothpaste has a low viscosity. However, although the shape retentionability of a dentifrice composition can be maintained by using a conventional thickener such as sodium carboxymethyl cellulose or carrageenan in conventional dentifrice compositions, the shape retentionability is still poor when the toothpaste has a low viscosity.
The present inventors have proposed, in Japanese Examined Patent Publication (Kokai) No. 60-75412, the provision of a toothpaste composition having a good shape retentionability when the viscosity is lowered to 600 poise or less, which is lower than the viscosities of conventional dentifrice compositions, by the addition of fumed ultra-fine amorphous silica.
Namely, the present inventors have proposed an effective realization of shape retentionability obtained by using a fumed ultra-fine amorphous silica in a dentifrice composition having a low viscosity, and thus obtained a suitable dentrifrice composition for use in a vertical pump type container.
In this connection, calcium phosphate, calcium carbonate, hydrated alumina, and silica type abrasives including precipitated silica are generally used as an abrasive base for conventional dentifrice compositions. However, when calcium phosphate, calcium carbonate, or hydrated alumina is used as an abrasive base in a dentifrice composition for a pump type container, the following problems arise:
(1) Since only a small amount of these abrasive bases can be formulated into the dentifrice composition, to maintain a good extrudability from a pump type container, the cleaning ability of the dentifrice composition is unsatisfactory. PA1 (2) Since a binder such as sodium carboxymethyl cellulose in the composition causes gellation and coagulation by multivalent metal ions dissolved from the powder of the above-mentioned abrasive bases, the extrudability of the dentifrice composition from the container sometimes becomes poor. Accordingly, silica type abrasive bases are mainly used as a base in dentifrice compositions for pump type containers.
However, although the shape retentionability of such dentifrice compositions with a low viscosity for pump type containers can be improved to a certain extent by formulating fumed silica therein, the shape retentionability thereof is likely to be decreased when stored at a high temperature, and sure the extrudability thereof from the container largely depends upon the temperature, a poorer extrudability occurs when lowered temperature. Furthermore, when fumed silica is used for improving the shape retentionability in the dentifrice compositions, and when silica abrasive bases are used in the dentifrice compositions, the structural viscosity of the dentifrice composition is changed with the elapse of time and, when the composition is stored for a long term, the extrudability thereof becomes poor.